void main() {
  int a = 13;
  int b = 5;

  print(a + b); //加
  print(a - b); //减
  print(a * b); //乘
  print(a / b); //除
  print(a % b); //其余
  print(a ~/ b); //取整

  var c = a * b;
  print('--------');
  print(c);
}
